The only reply you must get right every time is the one that wants out. Hostility comes with two-way texting; most of it needs no response and none of it needs an argument. What you cannot miss is an opt-out hiding inside an angry message, because ignoring it is the expensive mistake, not the harsh words.
Catch every form of 'stop'
People don't always text the magic word. 'Leave me alone,' 'remove me,' 'quit texting me,' 'unsubscribe,' all are opt-out requests you must honor, even phrased with profanity. Your system should catch the standard keywords automatically, and your humans should flag anything that reads as 'stop' in plain English and remove them.
Don't feed the fight
For hostility that isn't an opt-out, a brief, polite acknowledgment or no reply at all beats engagement. You will not win a text argument with an angry stranger, and trying generates complaints that hurt deliverability. Stay professional, de-escalate, and move on.
Frequently asked questions
What do I do when someone replies angrily to a campaign text?
Honor any opt-out instantly (including informal ones like 'leave me alone'), and don't argue. For hostility that isn't an opt-out, stay brief and polite or don't respond, never escalate.
Does 'leave me alone' count as a STOP request?
Treat it as one. Opt-out requests don't have to use the word STOP, 'remove me,' 'quit texting me,' 'unsubscribe,' and similar all require you to stop, even when phrased with profanity.
Informational, not legal advice.
Keep reading: What happens if I don't honor a STOP text and Can voters reply to campaign texts.